Patriarch of Moscow and All Russia Kirill conducts a prayer service ahead of Russian Olympic team departure to Rio 2016 Olympic Games at the Uspensky (Assumption) Cathedral in the Moscow's Kremlin, Russia July 27, 2016. REUTERS/Maxim Shemetov

MOSCOW (Reuters) - The head of the Russian Orthodox Church, Patriarch Kirill, will meet Britain's Queen Elizabeth during a visit to London this weekend, Russia's TASS news agency reported on Thursday.

The meeting between Kirill and Queen Elizabeth, who is Supreme Governor of the Church of England, comes at a time when relations between London and Moscow are strained over Syria and the Ukraine crisis.

British Foreign Secretary Boris Johnson said on Tuesday Russia risked becoming a "pariah nation" and accused it of targeting civilians in Syria. He called for protests outside the Russian embassy in London.